These Chevrolet Performance automatic transmission controllers include the wiring harness, controller, software, and laptop hookup. They are designed to allow for the use of electronically controlled transmissions in early model vehicles. Chevrolet Performance automatic transmission controllers are fully programmable for upshift, downshift, part throttle and wide-open shifts, and shift firmness. They come preprogrammed, just enter your rear tire diameter and rear axle ratio and go, or create your own custom shift characteristics. Chevrolet Performance automatic transmission controllers were originally developed by GM Racing for off-road truck racing. They have the ability to record and graph drag racing data like time, speed, shift point, engine rpm, and more.